1. Field
The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display in which signal lines disposed under a non-display region located out of a display region where an image is displayed, more specifically, a chip on glass (COG) region are prevented from being shorted.
2. Description of the Related Art
Recently, various flat displays capable of reducing weight and volume compare to cathode ray tube (CRT) displays are being developed.
The flat display devices include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting display (OLED), and the like.
The organic light emitting display displays an image by driving N×M organic light emitting devices, which are emissive display elements for electrically exciting an organic compound to emit light, by using a voltage or current.
Since the organic light emitting device has diode characteristics, the organic light emitting device is also referred to as an organic light emitting diode. The organic light emitting device includes an anode electrode that is a hole injection electrode, an organic thin film that is a light emitting layer, and a cathode electrode that is an electron injection electrode.
Accordingly, when holes and electrons are injected into the organic thin film, exitons obtained by combining the injected holes and electrons are transitioned from an excited state to a ground state, light is emitted from the organic light emitting device.
The OLEDs including the organic light emitting device having the aforementioned structure can be classified into a passive matrix type OLED and an active matrix type OLED depending upon driving types.
The structure of the active matrix type OLED will be described in detail.
The active matrix type OLED includes a first substrate provided with organic light emitting devices.
Here, the first substrate may be a driving circuit substrate including a driving circuit unit provided with TFTs.
The first substrate may be a display substrate not provided with the driving circuit unit, hereinafter, it is assumed that the first substrate is the driving circuit substrate.
The first substrate includes a display region, which is provided with organic light emitting devices, for displaying a predetermined image and a non-display region located out of the display region.
The display region is provided with a lower structure. A flattening layer is formed on the lower structure.
Here, the lower structure includes a plurality of thin film transistors and an interlayer insulation film for insulating the gate electrodes of the thin film transistors from the source and drain electrodes thereof.
In addition, an anode electrode electrically connected to the source and/or drain electrodes is formed on the flattening layer. The light emitting layer and a cathode electrode are sequentially formed on the anode electrode.
The organic light emitting device including the anode electrode, the light emitting layer, and the cathode electrode is separated from a neighboring sub-pixel by using a pixel defining layer.
At this time, the sub-pixel includes the light emitting layer for emitting red, green, or blue light.
Accordingly, a single pixel includes three sub-pixels for emitting light of each color of R, G and B. Full colors can be displayed by using a plurality of pixel.
The aforementioned organic light emitting display includes one or more driving ICs.
The driving ICs may be generally mounted by a tape automated bonding (TAB) or chip on glass (COG) method.
Here, the TAB method is a technique of mounting a tape carrier package (TCP) in which the driving IC is mounted on the substrate, and the COG method is a technique of directly mounting the driving IC on the substrate.
In the COG method, a driving IC having a finer pitch can be mounted as compared with a pitch used for the TAB method. Accordingly, recently, the COG method has been widely used.
However, to apply the COG method, the COG region on which the driving IC is mounted has to be included on the substrate. In the past, a part of the non-display region disposed out of the display region is used as the COG region.
Recently, a multi-panel process has been used to manufacture the organic light emitting display having the aforementioned structure.
Here, in the multi-panel process, a plurality of organic light emitting displays are formed on a mother glass, all the organic light emitting displays are enclosed by using encapsulation glass, and the encapsulation glass and the mother glass are cut in units of displays to provide a plurality of displays.
When the COG type organic light emitting display is manufactured in the multi-panel process, a part of the encapsulation glass is scribed and removed to expose the COG region, and the driving IC is mounted on the exposed COG region.
However, when the part of the encapsulation glass is removed, the flattening film is scratched by glass particles generated in the scribing process.
Accordingly, wirings under the COG region, which are formed on the same layer as the source and drain electrodes of the thin film transistor and protected by the flattening film, are shorted in the process of fabrication.